The present invention generally relates to a mounting construction of an elastic member, and more particularly to a mounting construction of an elastically pressing member which can be rapidly and easily mounted to a rod-like mounting member.
A magnetic recording/reproducing apparatus, such as a digital audio tape recorder, is known in which information is recorded on or reproduced from a magnetic tape by using a magnetic head provided in a rotary cylinder drum. In such a recording/reproducing apparatus, a swing idler is provided for rotating one of a supplying reel table and a winding reel table by selectively engaging with the one of the two reel tables. A reel lock mechanism is also provided for locking the reel tables, when the magnetic recording/reproducing apparatus is in a predetermined state, by engaging with the reel tables.
FIGS. 1 and 2 are cross-sectional views of examples of the swing idler provided in the above-mentioned conventional magnetic recording/reproducing apparatus. In FIGS. 1 and 2, the same parts are given the same reference numerals.
In FIGS. 1 and 2, an arm 3 has a plate-like shape, a fulcrum shaft 4 being mounted on one end of the arm 3 and an idle gear 5 being mounted on the other end. The fulcrum shaft 4 is pivotally mounted on a chassis (not shown in the figures) of the magnetic recording/reproducing apparatus. Accordingly, the arm 3 can swing about the fulcrum shaft 4.
The idle gear 5 selectively engages with one of a supplying reel table and a winding reel table (not shown in the figures) so as to transmit a driving force of a driving motor to rotate the one of the reel tables (hereinafter simply called "the reel table"). In the swing idler 1 shown in FIG. 1, the idle gear 5 is rotatably supported by a caulking pin 6. In the swing idler 2 shown in FIG. 2, the idle gear 5 is rotatably supported by a caulking bushing 7.
A driving gear coupled to an output shaft of the driving motor is engaged with the idle gear 5, and the arm 3 swings in directions corresponding to rotating directions of the driving gear. More specifically, a sliding clutch is formed between contacting parts of the arm 3 and the idle gear 5, and thus the arm 3 rotates about the fulcrum shaft 4 in a direction corresponding to a rotating direction of the driving motor. After the idle gear 5 is engaged with the reel table, which has teeth on its outer periphery gaging with the idle gear 5, the idle gear 5 serves as an intermediate gear between the driving motor and the reel table. That is, the idle gear 5 transmits a driving force of the driving motor to the reel table.
In order to constitute the above-mentioned sliding clutch, the idle gear 5 must be pressed onto the arm 3. To achieve this, an elastic member 8 (hereinafter simply called "spring") such as a tapered coil spring is provided in the swing idlers 1 and 2 so as to press the idle gear 5 onto the arm 3.
In the swing idler 1 shown in FIG. 1, an upper end (an engaging portion) 8a of the spring 8 is engaged with a collar 6a formed on an upper end of the caulking pin 6, and a lower end of the spring 8 is in contact with an upper surface of the idle gear 5. Accordingly, the idle gear 5 is pressed onto the arm 3 by a pressing force generated by the spring 8, and thus the sliding clutch is constituted. It should be noted that the caulking pin 6 is fixed to the arm 3 by caulking a caulking portion 6b formed on a lower end of the caulking pin 6 after inserting the caulking portion 6b into a mounting hole 3a formed in the arm 3.
In the above-mentioned swing idler 1, in order to attach the spring 8, the spring 8 and the idle gear 5 are fit on the caulking pin 6, in that order, before fixing the caulking pin 6 to the arm 3. In this state, the caulking portion 6b of the caulking pin 6 is inserted into the mounting hole 3a of the arm 3, and then the caulking portion 6b which protrudes from a reverse side of the arm 3 is caulked. By the above-mentioned mounting process, the spring 8 is assembled to the swing idler 1.
In the swing idler 2 shown in FIG. 2, the upper end (an engaging portion) 8a of the spring 8 is engaged with a collar 9a formed on a press fitting pin 9 press fit in the caulking bushing 7. The lower end of the spring 8 is in contact with the upper surface of the idle gear 5. The caulking bushing 7 is fixed to the arm 3 by caulking a caulking portion 7a formed on a lower end of the caulking bushing 7 after inserting the caulking portion 7a into the mounting hole 3a formed in the arm 3.
In the above-mentioned swing idler 2, in order to attach the spring 8, the caulking bushing 7 is inserted into the mounting hole 3a of the arm 3 first, and then the caulking portion 7a protruding from the reverse side of the arm 3 is caulked. Accordingly, the caulking bushing 7 is fixed to the arm 3. After that, the idle gear 5 and the spring 8 are fit on the caulking bushing 7, in that order, and then the press fitting pin 9 is press fit in a press fit hole 7b formed in the caulking bushing 7 fixed on the arm 3, and thus the spring 8 is assembled to the swing idler 2.
FIGS. 3 and 4 are cross-sectional views of examples of a reel lock mechanism provided in a conventional recording/reproducing apparatus. In FIGS. 3 and 4, the same parts are given the same reference numerals.
A reel lock mechanism 10 shown in FIG. 3 is provided with a reel lock gear 12 which rotates by being coupled to a driving motor (not shown in the figure). A shaft 12a extends upwardly from the center of the reel lock gear 12. The reel lock gear 12 is rotatably mounted on a support shaft 14 mounted on a chassis of the magnetic recording/reproducing apparatus.
A reel lock 13 is provided on the reel lock gear 12. The reel lock 13 is rotatably supported on the shaft portion 12a formed on the reel lock gear 12. Additionally, a locking claw extending laterally is formed on an outer periphery of the reel lock 13. A reel table (not shown in the figure) is locked by the locking claw 15 being engaged with teeth formed on an outer periphery of the reel table.
A spring 17 is attached on the shaft portion 12a of the reel lock gear 12, and then a cap 16 having a collar 16a is press fit over the shaft portion 12a. The collar 16 is engaged with an upper portion (an engaging portion) of the spring 17. The spring 17 presses the reel lock 13 against the reel lock gear 12 by the upper portion (the engaging portion) of the spring 17 being engaged with the collar 16a. Accordingly, a sliding clutch is constituted between contact portions of the reel lock gear 12 and the reel lock 13.
It should be noted that a slit washer 18 is fit on an upper end of the cap 16. The slit washer 18 engages with an annular groove 14a formed on the upper end of the support shaft 14, and thereby the slit washer 18 is fixed to the support shaft 14. Accordingly, the cap 16 does not come off from the shaft 14 when the cap 16 is pressed upwardly by the spring 17.
A reel lock mechanism 11 shown in FIG. 4 comprises a reel lock gear 19, a reel lock 20 and a spring 21. In the reel lock mechanism 11, the reel lock gear 19 and the reel lock 20 are rotatably mounted on the support shaft 14 mounted on a chassis of the magnetic recording/reproducing apparatus.
In the reel lock mechanism 11, the spring 21 is attached by fitting the spring 21 on the support shaft 14 first. Then a thrust washer 22 engaging with an engaging portion 21a formed on an upper portion of the spring 21 is fit on the support shaft. Thereafter, a slit washer 23 is fit on the support shaft 14. The slit washer 23 is engaged with the annular groove 14a formed on the upper end of the support shaft 14, and thereby the slit washer 23 is fixed on the support shaft 14. Accordingly, the thrust washer 22 does not come off from the shaft 14 when the thrust washer 22 is pressed upwardly by the spring 21.
In the above-mentioned mounting constructions of the springs 8 and 21, there are problems mentioned below.
In the mounting construction of the spring 8 shown in FIG. 1, there is a problem in that an assembling operation is inconvenient because the spring 8 and the idle gear 5 are fit, in turn, on the caulking pin 6, and then the caulking portion 6b of the caulking pin 6 is inserted into the mounting hole 3a of the arm 3 while this state is maintained, and further a caulking operation for the caulking portion 6b must be performed while pressing the caulking pin 6 against an elastic force generated by the spring 8.
In the mounting construction of the spring 8 shown in FIG. 2, there is a problem in that many parts are needed and thus a manufacturing cost is increased although an assembling operation becomes easier than that of the mounting construction shown in FIG. 1 because the caulking bushing 7 is inserted into the mounting hole 3a of the arm 3, and then the caulking portion 7a protruding from the reverse side of the arm 3 is caulked, and thereafter the idle gear 5 and the spring 8 are fit, in turn, on the caulking bushing 7 fixed on the arm 3, and then the press fitting pin 9 is press fit to the caulking bushing 7.
In the mounting construction of the spring 21 shown in FIG. 3, although the reel lock gear 12 and the reel lock 13 are assembled in a single unit before they are mounted on the support shaft 14 which condition is convenient for the assembling operation, there is a problem in that many parts are used and thus a manufacturing cost is increased as is the case for the mounting construction shown in FIG. 2.
In the mounting construction of the spring 21 shown in FIG. 4, there is a problem in that an assembling operation is inconvenient because the thrust washers 22 and the slit washer 23 must be mounted on the support shaft 14 while pressing the spring 21. Additionally, unlike the construction shown in FIG. 3, the reel lock gear 12 and the reel lock 13 are not handled as a single unit, and thus there is a problem in that a measurement of torque, which is generated by a friction between the reel lock gear 12 and the reel lock 13, cannot be performed until the entire reel lock mechanism is assembled.
Further, in each of the mounting constructions of the swing idlers, after the spring 8 is initially mounted, the spring 8 cannot be removed form the swing idlers 1 and 2. Accordingly, if a malfunction occurs in one of the swing idlers, the entire one of the swing idlers must be replaced, and thus there is a problem in that a maintenance cost is high.